The Newtonian Revolution

Revolutions, scientific and social, consist of more than an initial press release followed by a victory celebration. Often, they are drawn out wars between opposing forces, with the outcome long in doubt. Copernicus declared a heliocentric system in 1543, but more than half a century later Galileo was fighting valiantly; nor did he win every battle. Near the end of the seventeenth century Isaac Newton quantitatively reproduced Kepler's mathematical kinematics of the heavens with a new celestial dynamics based on an inverse-square force. It remained to be seen if Newton's gravity could win out over the French philosopher René Descartes' vortices, and if gravity did triumph, what repercussions the victory might have beyond astronomy.

A propaganda effort on Newton's behalf was already underway even before the Principia appeared in print. Edmond Halley wrote to a German professor of mathematics and physics to inform him of the new theory of universal gravitation brilliantly investigated by Newton. And Halley also wrote to the physician to the duke of Würtemburg to inform him of "a truly outstanding book" written by perhaps the greatest geometer ever to exist, which would prove "how far the human mind properly instructed can avail in seeking truth" (Feingold, Newtonian Moment, 31). Also before the Principia was published, there appeared in the Philosophical Transactions of the Royal Society of London (edited by Halley) an anonymous review (written by Halley) of Newton's incomparable treatise, which provided "a most notable instance of the extent of the powers of the Mind," and showed "what are the principles of Natural Philosophy, and so far derived from them their consequences" that Newton seemed "to have exhausted his Argument, and left little to be done by those that shall succeed him" (Feingold, Newtonian Moment, 31).

Actually, the concerted efforts of many mathematician-astronomers during much of the following century would be required to work out details left undone by Newton. To write the history of eighteenth-century astronomy is to write about the continuation of the research program, or paradigm, set by Newton.

In hindsight, victory was inevitable. For nearly a century, however, Newtonians battled a strong rival army. In the middle of the seventeenth century, before Newton's work, Descartes had proposed that the universe consists of huge whirlpools, or vortices, of cosmic matter. Our solar system was one of many whirlpools, its planets all moving in the same direction in the same plane around a luminous central body. Moons also were carried by vortices around their planets.

The French literary giant François-Marie Arouet de Voltaire wittily summed up the situation in his 1733 Lettres philosophiques, also known as Lettres anglaises, or Letters Concerning the English Nation. A Frenchman arriving in London would find philosophy, like everything else, very much changed there. He left the world full, and found it empty; he left the world a plenum, and found it a vacuum. In Paris the universe was seen composed of vortices of subtle matter; but nothing like vortices were to be seen in London. In Paris everything was explained by a pressure that nobody understood; in London everything was explained by an attraction that nobody understood either.

Publication in 1737 of Voltaire's Elémens de la philosophie de Newton (Elements of Newton's Philosophy), according to a reviewer, resulted in all Paris resounding with Newton, all Paris stammering Newton, and all Paris studying and learning Newton. Madame du Châtelet, who had assisted Voltaire with the Elements (the frontispiece depicts her held in the sky by winged cherubs, one breast bared, and holding a mirror reflecting rays of light coming from behind Newton—who is wearing a toga and is seated on a throne of clouds—to Voltaire, busy writing at his earthbound desk), also reviewed the Elements, favorably and anonymously. In a private letter, this Minerva (the goddess of reason) of France wrote that publication of Voltaire's books was necessary because the French were blissfully ignorant of flaws in Cartesianism evident to everyone else in Europe and thus were unable to participate in the progress which Newton's discoveries would make possible.

Voltaire likened himself to a man blind in one eye expostulating with men blind in both eyes. (Earlier, Voltaire had written that "Before Kepler all men were blind; Kepler was one-eyed, and Newton had two eyes" [Feingold, Newtonian Moment, 31]). Voltaire also likened Newton, the greatest man who had ever lived, to the

Voltaire's Lettres Anglaises

Royal permission for publication of Voltaire's Letters Concerning the English Nation had been withheld, and enraged authorities issued a warrant for his arrest. Tipped off by one of the King's ministers, Voltaire had already fled to Madame du Chatelet's chateau, conveniently located, were he pursued, near the border with Lorraine, then an independent province. The couple enjoyed both a romantic and an intellectual relationship. Her husband tolerated the presence of Voltaire, who loaned the Marquis money to renovate the chateau.

Voltaire had left behind in Paris his publisher, who was thrown into the Bastille, and copies of his impious book implying that French civilization was deficient, which were burnt by the public hangman. Scandal and the distinction of being banned in Paris fueled sales of the book, which topped 20,000 within five years.

kingdom of heaven, and the French to the little children in Matthew 19:14: "But Jesus said, Suffer little children, and forbid them not, to come unto me: for of such is the kingdom of heaven." Voltaire was instrumental in spreading the Newtonian revolution; as late as 1774 his books were still praised as the only source for gentlemen not learned in the sciences to turn to for information about Newton. That was in France. In England, as early as 1702, a few university students, if not cultured gentlemen and ladies, had access to Newton's science in two new textbooks: John Keill's Introductio ad varem physicam (Introduction to the True Physics) and David Gregory's Astronomiœ, physicœ et geometriœ elementa (Elements of Astronomy, Physical and Geometrical).

In the same year as the appearance of Voltaire's Elements of Newton's Philosophy, the Newtonian revolution gained yet more ground, from measurements of the shape of the Earth. Newton had predicted that the Earth was flattened at the poles; Cartesians said it must be flattened at the equator. As Voltaire put it: "In Paris you see the Earth shaped like a melon, in London it is flattened on two sides" (Feingold, Newtonian Moment, 100). Local measurements by Jacques Cassini, one of four generations of Cassinis to direct the Paris Observatory from its founding in 1669 until they were driven out in 1793 during the French Revolution, supported the Cartesians. PierreLouis Moreau de Maupertuis, a young French mathematician sent by the Académie des Sciences to Lapland to make more decisive measurements, returned in 1737 as the "flattener of Earth and of the Cassinis," so Voltaire